Observation instruments such as endoscopes are used in medical and other applications to allow a visual inspection of locations which are not readily accessible. For example, endoscopes are used in medical applications to provide a view of an area within a patient's body. An endoscope typically includes an elongated shaft of relatively small diameter extending from a handle to a distal end. An imaging or viewing arrangement is included with the endoscope to allow a user to obtain a view from the distal end. This arrangement may include a system of lenses and a light conduit through the shaft to direct an image from the distal end to an eyepiece associated with the endoscope handle. Alternatively, the imaging or viewing arrangement may include an electronic imaging device at the distal end of the endoscope. Such an electronic imaging device collects image data and communicates that data through the shaft and handle ultimately to a processing system that assembles the data into an image displayed on a suitable display device. Whether the location at the distal end of the endoscope is viewed directly, or imaged electronically, the location must be illuminated sufficiently.
To provide the desired illumination, light may be generated by a light source at the endoscope handle and directed through suitable conduits in the shaft (such as optical fibers for example) to the endoscope distal end were the light can be directed as desired through suitable lenses. Alternatively to relying on light conducted through the shaft to the distal end of the endoscope, a suitable light source such as an LED lamp may be placed at the distal end of the endoscope to provide the required illumination. Although placement of a light source at the distal end of the endoscope provides a number of advantages, such an arrangement raises certain challenges. One challenge is that the light source and its associated electrical connections must remain small enough to fit in the distal end of the endoscope along with the objective lens for the imaging/viewing system and other elements which may be included at the distal end. Another challenge, particularly in medical applications, is that the light source must be capable of providing the desired illumination without heating the distal end of the endoscope beyond acceptable levels. Generally, the distal end of the endoscope must remain below 40° C. Thus any distal end light source must be capable of operating without releasing excessive heat to other elements within the distal end assembly.
Thermal management systems have been developed for addressing the issue of heat generated by illumination devices in endoscopes. U.S. Patent Application Publication No. 2011/0306834 discloses an endoscope with a heat pipe arranged to conduct heat away from a light source at the distal end of an endoscope. The arrangement shown in this prior publication includes a light source thermally coupled to two heat coupling elements which are in turn thermally coupled to the heat pipe. The heat pipe extends from the distal end of the endoscope to a heat sink at the opposite end of the shaft. Electrical power for the light source in U.S. Patent Application Publication No. 2011/0306834 is provided through wires which extend through the endoscope shaft alongside the heat pipe and heat coupling elements. While this prior system provides an arrangement for conducting heat away from a light source at a distal end of the endoscope, it does so at the cost of the added heat pipe taking up space within the shaft of the endoscope.
U.S. Patent Application Publication No. 2016/0000309 discloses an LED assembly in which an LED is mounted on a first conductor which is surrounded by a conductive sleeve. One electrical contact of the LED is coupled to the first conductor, while the other electrical contact of the LED is connected to the sleeve via a conductive tab. Both the first conductor and the conductive sleeve in this arrangement can dissipate waste heat from the LED. However, the sleeve required in the structure disclosed in U.S. Patent Publication No. 2016/0000309 increases the transverse dimension of the LED assembly, and also complicates manufacturing.
There remains a need for compact arrangements which can effectively conduct heat away from a light source mounted at the distal end of an observation instrument such as an endoscopic device.